How many have died in school shootings since Sandy Hook?

It has been a decade since a gunman opened fire at Sandy Hook Elementary in Connecticut, killing 20 children and six school staff.

The tragedy spurred an outpouring of demand for tighter gun control.

Yet the death toll from school shootings keeps climbing as debates over gun control continue.

Since the Sandy Hook massacre, there have been 189 shootings on school grounds, claiming some 279 more lives.

In November, a memorial for the victims of Sandy Hook was opened to the public, not far from the school grounds.

Victims' names were carved into a wall that circled a sycamore tree.

Nelba Marquez-Greene's six-year old daughter, Ana Grace Marquez-Greene, was among the victims.

"Ten years. A lifetime and a blink," she wrote on Twitter. "Ana Grace, we used to wait for you to come home. Now you wait for us. Hold on, little one. Hold on."

"We're not in a place to have polite discourse in this country on that issue," she said.

In the aftermath of what was at the time the worst school shooting in US history, then-President Barack Obama vowed to push forward sweeping legislation to reduce gun violence by addressing everything from gun magazine sizes to mental health.

But he left office without being able to pass his hoped-for laws.

Ten years on, the current Democratic president, Joe Biden, has renewed a promise to pass a ban on semi-automatic weapons.

In June, Mr Biden signed a landmark gun bill into law, but if fell short of reinstating the so-called assault-weapons ban that had been in effect before 2004.

However, a debate over this and other gun control measures that have been proposed continues, with evidence being put forward on both sides over their effectiveness at stopping school shootings.

Gun control advocates argue that tighter restrictions to access is key, while others argue that failures of the mental health system and better security on school campuses are more pressing concerns.

Meanwhile, there have been 279 victims of all ages killed in 189 school shootings with at least one casualty over the past decade - including those killed in Sandy Hook - according to the K-12 School Shooting Database, an independent, non-partisan research group.

Those shootings include deaths from suicides and domestic violence as well as 17 "active shooter situations" - defined as "when the shooter killed and/or wounded victims, either targeted or random, within the school campus during a continuous episode of violence".

While those events count for a small portion of total shooting incidents, they account for more than a third of all casualties.

Nicole Hockley, the co-founder of Sandy Hook Promise Foundation, a charity, lost her son Dylan in the massacre.

"All shootings reopen wounds," she told the BBC earlier this year.

Her other son, who survived, graduated from high school this year and will be able to vote. It is his generation, she said, who will enact change.